Secondary control method and device for parallel inverters in microgrid

Abstract

The invention discloses a micro grid parallel inverter secondary control method and device; the method comprises the following steps: 1, using sagging control to form a fundamental wave voltage frequency instruction value and an amplitude instruction value in a voltage instruction of an inverter according to the inverter output voltage and output current, thus obtaining a fundamental wave voltage instruction value; 2, extracting a voltage value and a current value of a first AC signal and a second AC signal from the inverter output voltage and output current, using sagging control to form a frequency instruction value of the first AC signal so as to obtain a voltage instruction value of the first AC signal, and using sagging control to form a frequency instruction value of the second AC signal so as to obtain a voltage instruction value of the second AC signal; 3, adjusting the inverter output voltage according to the first AC signal voltage instruction value, the second AC signal voltage instruction value, and the fundamental wave voltage instruction value. The method and device can effectively eliminate frequency and voltage amplitude deviations caused by sagging control, and all inverters can realize power equalization.

Description

technical field [0001] The invention belongs to the field of coordinated control of parallel inverters in a microgrid, and in particular relates to a secondary control method and device for parallel inverters in a microgrid based on AC small signals without interconnection lines. Background technique [0002] With the deepening of environmental and energy crisis, the concept of microgrid has received more and more attention and application. A microgrid (also known as a microgrid) is an energy system that combines distributed power sources and interconnected loads. In most cases, the microgrid is connected to the busbar through a power electronic interface, such as an inverter. Therefore, the coordinated control among parallel inverters is one of the key factors for the stable and efficient operation of the microgrid. [0003] Due to the geographic dispersion of distributed power supplies, it is often not a good idea to use communication lines to transmit signals between pa...

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Problems solved by technology

Although this method does not have high requirements on the power capacity of the main inverter, because it uses the dead zone to overcome the synchronization problem of parallel inverters, the adjustment process is relatively slow, and it is not suitable for occasions where the load changes rapidly; and this method requires the system The control parameters of all inverters in the system are stored in the controller of each inverter, so when an inverter is added or removed from the system, the parameters of other inverters must be modified accordingly, which is cumbersome

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